Luminaire

ABSTRACT

According to one embodiment, a luminaire includes a board provided in a main body part, a light-emitting element provided on a surface of the board, a surrounding wall member provided to surround the light-emitting element, and a joining part including a first portion which is provided between the board and the surrounding wall member and a second portion which is provided outside the surrounding wall member and covers at least a part of an outer wall of the surrounding wall member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2013-076902, filed on Apr. 2, 2013; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a luminaire.

BACKGROUND

There is a luminaire including plural light emitting diodes (LEDs)mounted on a board, an annular surrounding wall member provided on theboard so as to surround the plural light emitting diodes, and a sealingmember filled inside the annular surrounding wall member.

In the luminaire as stated above, one end face of the surrounding wallmember and the board are bonded by using an adhesive.

In such a case, if the coating amount of the adhesive is irregular, aportion where the adhesive is insufficient is formed between thesurrounding wall member and the board. If the portion where the adhesiveis insufficient is formed, bonding strength (fixing strength) becomesirregular, and a portion which is weak against external stress orthermal shock is partially formed. Thus, there is a fear thatairtightness between the surrounding wall member and the board isreduced, performance is reduced by penetration of moisture and gas, andconduction failure or the like occurs due to peeling of the sealingmember.

Besides, as the area of the board exposed at the inside of thesurrounding wall member becomes small, light extraction efficiencybecomes high. In this case, when the plural light-emitting diodes aremounted or the surrounding wall member is bonded, variability can occurat respective positions. Thus, a gap is needed between the plurallight-emitting diodes or between the surrounding wall member and theplural light-emitting diodes. Accordingly, the area of the board exposedat the inside of the surrounding wall member can not be reduced, andthere is also a problem that improvement of the light extractionefficiency is difficult.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view for exemplifying a luminaire 1 ofan embodiment.

FIG. 2 is a schematic exploded view for exemplifying the luminaire 1.

FIG. 3 is an A-A line sectional view in FIG. 2.

FIG. 4 is a schematic sectional view for exemplifying a form of a thirdportion 28 c.

FIG. 5 is a schematic sectional view for exemplifying the form of thethird portion 28 c.

DETAILED DESCRIPTION

According to a first embodiment, a luminaire includes a board providedin a main body part, a light-emitting element provided on a surface ofthe board, a surrounding wall member provided to surround thelight-emitting element, and a joining part including a first portionwhich is provided between the board and the surrounding wall member anda second portion which is provided outside the surrounding wall memberand covers at least a part of an outer wall of the surrounding wallmember.

According to this luminaire, airtightness between the surrounding wallmember and the board, resistance against external stress and thermalshock, and light extraction efficiency can be improved.

According to a second embodiment, in the luminaire of the firstembodiment, the joining part further includes a third portion which isprovided inside the surrounding wall member and covers at least a partof an inner wall of the surrounding wall member.

According to this luminaire, the airtightness between the surroundingwall member and the board, the resistance against external stress andthermal shock, and the light extraction efficiency can be furtherimproved.

According to a third embodiment, in the luminaire of the firstembodiment, reflectivity of the joining part to light emitted from thelight-emitting element is higher than that of the board or a wiringpattern.

According to this luminaire, the light extraction efficiency can befurther improved.

According to a fourth embodiment, in the luminaire of the firstembodiment, a following expression is satisfied:

Wc≧L/2

where a width of the third portion is Wc, and a distance between aninner wall of the surrounding wall member and an end face of thelight-emitting element is L.

According to this luminaire, the light extraction efficiency can befurther improved.

According to a fifth embodiment, in the luminaire of the firstembodiment, the light-emitting element is electrically connected to awiring pattern provided on the surface of the board, and the luminairefurther includes a power-supply terminal which is electrically connectedto the wiring pattern, and a socket which is fitted to the power-supplyterminal.

According to a sixth embodiment, in the luminaire of the firstembodiment, the first portion is membranous.

According to a seventh embodiment, in the luminaire of the firstembodiment, a thickness of the second portion is larger than a thicknessof the first portion.

According to an eighth embodiment, in the luminaire of the firstembodiment, the second portion includes a first surface inclined in adirection in which as a part thereof approaches the board side, the partgoes away from the outer wall of the surrounding wall member.

According to a ninth embodiment, in the luminaire of the eighthembodiment, the first surface is one of a concave curved surface, aconvex curved surface and a flat surface.

According to a tenth embodiment, in the luminaire of the secondembodiment, a thickness of the third portion is larger than a thicknessof the first portion.

According to an eleventh embodiment, in the luminaire of the secondembodiment, a thickness of the third portion is smaller than a thicknessof the second portion.

According to a twelfth embodiment, in the luminaire of the secondembodiment, the third portion includes a second surface inclined in adirection in which as a part thereof approaches the board side, the partgoes away from the inner wall of the surrounding wall member.

According to a thirteenth embodiment, in the luminaire of the twelfthembodiment, the second surface is one of a concave curved surface, aconvex curved surface and a flat surface.

According to a fourteenth embodiment, in the luminaire of the secondembodiment, the third portion covers a surface of the board exposed atthe inside of the surrounding wall member.

According to a fifteenth embodiment, in the luminaire of the firstembodiment, the joining part includes a resin and a particle made of amaterial having a high reflectivity to light emitted from thelight-emitting element.

According to a sixteenth embodiment, in the luminaire of the fifteenthembodiment, the resin is one of silicone resin and epoxy resin, and thematerial having the high reflectivity to the light emitted from thelight-emitting element is titanium oxide.

According to a seventeenth embodiment, in the luminaire of the secondembodiment, the inner wall of the surrounding wall member is parallel toa front direction of the luminaire.

According to an eighteenth embodiment, in the luminaire of the firstembodiment, the surrounding wall member is annular-shaped.

According to a nineteenth embodiment, the luminaire of the firstembodiment further includes a sealing part provided at a center part ofthe surrounding wall member.

According to a twentieth embodiment, in the luminaire of the nineteenthembodiment, the sealing part includes a translucent material and aphosphor.

Hereinafter, one embodiment will be exemplified with reference to thedrawings. Incidentally, in the respective drawings, the same componentsare denoted by the same reference numerals, and their detailedexplanation will be appropriately omitted.

FIG. 1 and FIG. 2 are schematic perspective views for exemplifying aluminaire 1 of this embodiment.

Incidentally, FIG. 1 is a schematic perspective view of the luminaire 1,and FIG. 2 is a schematic exploded view of the luminaire 1.

In FIG. 1 and FIG. 2, a sealing part 27 is omitted in order to make thedrawings easy to see.

FIG. 3 is an A-A line sectional view in FIG. 2.

As shown in FIG. 1 and FIG. 2, the luminaire 1 includes a main body part10, a light-emitting part 20, a power-supply part 30 and a socket 40.

The main body part 10 includes a housing part 11, a flange part 12 andfins 13. The housing part 11 is cylindrical and protrudes from onesurface of the flange part 12. The light-emitting part 20 is housedinside the housing part 11. Besides, a power-supply terminal 31 of thepower-supply part 30 protrudes inside the housing part 11.

The flange part 12 is disk-shaped, one surface thereof is provided withthe housing part 11, and the other surface is provided with the fins 13.

The plural fins 13 are provided to protrude from the surface of theflange part 12. The plural fins 13 are plate-shaped, and function asthermal radiation fins.

The main body part 10 has the function of housing the light-emittingpart 20, the power-supply part 30 and the like and the function ofradiating heat generated in the light-emitting part 20 and thepower-supply part 30 to the outside of the luminaire 1.

Thus, taking it into account that the heat is radiated to the outside,the main body part 10 can be formed of a material having a high thermalconductivity. For example, the main body part 10 can be formed ofaluminum, aluminum alloy, high thermal conductivity resin or the like.The high thermal conductivity resin is such that for example, resin suchas PET or nylon is mixed with fibers or particles of carbon having highthermal conductivity or aluminum oxide.

In this case, a portion to radiate the heat to the outside, such as thefins 13, is formed of a material having a high thermal conductivity, andthe other portion can be formed of resin or the like.

Besides, when a main portion of the main body part 10 is formed of aconductive material, in order to ensure the electrical insulationbetween the power-supply terminal 31 and the conductive material of themain body part 10, the periphery of the power-supply terminal 31 iscovered with an insulating material (not shown), and further, theconductive material may be arranged on the periphery thereof. Theinsulating material is, for example, resin, and is preferably a materialhaving a high thermal conductivity. Besides, the main body part 10 maybe provided with an attachment part detachable from and attachable to avehicle lighting fixture.

As shown in FIG. 3, the light-emitting part 20 includes a board 21,light-emitting elements 22, a surrounding wall member 26, a sealing part27 and a joining part 28.

The board 21 is provided inside the housing part 11 of the main bodypart 10.

The board 21 is plate-shaped, and the surface is provided with a wiringpattern 24.

The material and structure of the board 21 are not particularly limited.For example, the board 21 may be formed of an inorganic material(ceramic) such as aluminum oxide or aluminum nitride, or an organicmaterial such as paper phenol or glass epoxy. Besides, the board 21 maybe such that a surface of a metal plate is coated with an insulator.Incidentally, when the surface of the metal plate is coated with theinsulator, the insulator may be made of an organic material or aninorganic material.

In this case, when the amount of heat generation of the light-emittingelements 22 is large, from the viewpoint of thermal radiation, the board21 is preferably formed of a material having a high thermalconductivity. As the material having the high thermal conductivity, forexample, ceramics such as aluminum oxide or aluminum nitride, highthermal conductivity resin, a metal plate whose surface is coated withan insulator, and the like can be exemplified.

Besides, the board 21 may be a single-layer board or a mufti-layerboard.

The plural light-emitting elements 22 are mounted on the wiring pattern24 provided on the surface of the board 21.

The light-emitting element 22 can include a not-shown electrode on asurface (upper surface) at an opposite side to a side where thelight-emitting element is provided on the wiring pattern 24.Incidentally, the not-shown electrode may be provided on a surface(lower surface) at the side where the light-emitting element is providedon the wiring pattern 24 and the surface (upper surface) at the oppositeside to the side where the light-emitting element is provided on thewiring pattern 24, or may be provided on only one of the surfaces.

The electrode provided on the lower surface of the light-emittingelement 22 is electrically connected to a not-shown mount pad providedon the wiring pattern 24 through a conductive thermosetting materialsuch as silver paste. The not-shown electrode provided on the uppersurface of the light-emitting element 22 is electrically connected to anot-shown wiring pad provided on the wiring pattern 24 through a wiring25.

The light-emitting element 22 is, for example, a light-emitting diode,an organic light-emitting diode or a laser diode.

A light-emitting surface of the light-emitting element 22 is directed tothe front side of the luminaire 1, and emits light mainly toward thefront side of the luminaire.

The number and size of the light-emitting elements 22 are not limited toexemplified ones, and can be appropriately changed according to the sizeand use of the luminaire 1.

The wiring pattern 24 is provided on at least one of the surfaces of theboard 21.

Although the wiring pattern 24 may be provided on both the surfaces ofthe board 21, in order to reduce the manufacturing cost, the wiringpattern is preferably provided on one of the surfaces of the board 21.

The wiring pattern 24 is provided with input terminals 24 a.

The plural input terminals 24 a are provided. The power-supply terminals31 of the power-supply part 30 are electrically connected to the inputterminals 24 a. Thus, the light-emitting elements 22 are electricallyconnected to the power-supply part 30 through the wiring pattern 24.

The wiring 25 electrically connects the not-shown electrode provided onthe upper surface of the light-emitting element 22 to the not-shownwiring pad provided on the wiring pattern 24.

The wiring 25 is, for example, a wire mainly containing gold. However,the material of the wiring 25 is not limited to the material mainlycontaining gold, and for example, a material mainly containing copper ora material mainly containing aluminum may be used.

The wiring 25 is electrically connected to the not-shown electrodeprovided on the upper surface of the light-emitting element 22 and thenot-shown wiring pad provided on the wiring pattern 24 by ultrasonicwelding or thermal welding. The wiring 25 can be electrically connectedto the not-shown electrode provided on the upper surface of thelight-emitting element 22 and the not-shown wiring pad provided on thewiring pattern 24 by using, for example, a wire bonding method.

In addition, a circuit component such as a not-shown control element tocontrol current flowing through the light-emitting element 22 can beappropriately provided. The circuit component such as the not-showncontrol element can be mounted on the wiring pattern 24.

The surrounding wall member 26 is provided on the board 21 so as tosurround the plural light-emitting elements 22. The surrounding wallmember 26 has, for example, an annular shape, and the plurallight-emitting elements 22 are exposed at a center part 26 a.

The shape of the surrounding wall member 26 may be an elliptical shapeor a polygonal shape such as a square, a hexagon or an octagon, and theshape is not particularly limited.

The surrounding wall member 26 can be formed of, for example, a resin,such as PBT (polybutylene terephthalate) or PC (polycarbonate), orceramics.

When the material of the surrounding wall member 26 is the resin, thereflectivity to light emitted from the light-emitting element 22 can beimproved by mixing particles of titanium oxide or the like.

Incidentally, no limitation is made to the particles of titanium oxide,and particles made of a material having a high reflectivity to the lightemitted from the light-emitting element 22 has only to be mixed.

A side wall surface on the center 26 a side of the surrounding wallmember 26 is an inclined surface. Part of the light emitted from thelight-emitting element 22 is reflected by the side wall surface on thecenter part 26 a side of the surrounding wall member 26, and is emittedtoward the front side of the luminaire 1. That is, the surrounding wallmember 26 can be made to have also the function of a reflector.Incidentally, the form of the surrounding wall member 26 is not limitedto the exemplified one and can be appropriately changed.

The sealing part 27 is provided at the center part 26 a of thesurrounding wall member 26. The sealing part 27 is provided so as tocover the inside of the surrounding wall member 26.

The sealing part 27 is formed of a translucent material. The sealingpart 27 can be formed of, for example, silicone resin.

The sealing part 27 can be formed by filling, for example, a resin inthe center part 26 a of the surrounding wall member 26. The filling ofthe resin can be performed by using, for example, a liquid constantquantity discharging apparatus such as a dispenser.

When the resin is filled in the center part 26 a of the surrounding wallmember 26, mechanical contact from the outside to the light-emittingelements 22, the wiring pattern 24 exposed at the center part 26 a ofthe surrounding wall member 26 and the wiring 25 can be suppressed.Besides, the attachment of air or moisture to the light-emittingelements 22, the wiring pattern 24 exposed at the center part 26 a ofthe surrounding wall member 26 and the wiring 25 can be suppressed.Thus, the reliability of the luminaire 1 can be improved.

Besides, the sealing part 27 can include a phosphor. The phosphor is,for example, a YAG phosphor (Yttrium Aluminum Garnet phosphor).

For example, when the light-emitting element 22 is a blue light-emittingdiode, and the phosphor is the YAG phosphor, the YAG phosphor is excitedby the blue light emitted from the light-emitting element 22, and yellowfluorescence is emitted from the YAG phosphor. The blue light and theyellow light are mixed, so that white light is emitted from theluminaire 1. Incidentally, the kind of the phosphor and the kind of thelight-emitting element 22 are not limited to the exemplified ones, andcan be appropriately changed according to the use of the luminaire 1 sothat a desired light-emitting color can be obtained.

The joining part 28 joins the surrounding wall member 26 to the board21.

Incidentally, the details of the joining part 28 will be describedlater.

The power-supply part 30 is provided with the plural power-supplyterminals 31.

The plural power-supply terminal 31 extends in the inside of the housingpart 11 and the flange part 12. One ends of the plural power-supplyterminals 31 protrude from a bottom surface of the housing part 11 andare electrically connected to the input terminals 24 a of the wiringpattern 24. The other ends of the plural power-supply terminals 31 areexposed from the opposite side to the side of the main body part 10where the board 21 is provided.

Incidentally, the number, arrangement, form and the like of thepower-supply terminals 31 are not limited to the exemplified ones andcan be appropriately changed.

Besides, the power-supply part 30 can also include a not-shown board anda circuit component such as a capacitor or a resistor. Incidentally, thenot-shown board and the circuit component can be provided, for example,inside the housing part 11 or the flange part 12.

The socket 40 is fitted to the ends of the plural power-supply terminals31 exposed to the opposite side to the side of the main body part 10where the board 21 is provided.

A not-shown power supply and the like are electrically connected to thesocket 40.

Thus, when the socket 40 is fitted to the ends of the power-supplyterminals 31, the not-shown power supply and the like are electricallyconnected to the light-emitting elements 22.

The socket 40 can be connected to components on the main body 10 side byusing an adhesive or the like.

Next, the joining part 28 will be further described.

As shown in FIG. 3, the joining part 28 includes a first portion 28 a, asecond portion 28 b and a third portion 28 c.

The first portion 28 a, the second portion 28 b and the third portion 28c are integrally formed.

The first portion 28 a is provided between the surrounding wall member26 and the board 21.

The first portion 28 a is membranous.

The second portion 28 b is provided outside an outer wall 26 b of thesurrounding wall member 26, and covers at least a part of the outer wall26 b of the surrounding wall member 26.

A thickness Tb of the second portion 28 b is larger than a thickness Taof the first portion 28 a.

The thickness Tb of the second portion 28 b and a width Wb of the secondportion 28 b are not particularly limited.

Incidentally, the thickness Tb of the second portion 28 b is a size fromthe surface of the board 21 to the highest position attached to theouter wall 26 b of the surrounding wall member 26.

The width Wb of the second portion 28 b is a size from the outer wall 26b of the surrounding wall member 26 to the farthest position from theouter wall 26 b attached to the surface of the board 21.

If the width Wb of the second portion 28 b and the thickness Tb of thesecond portion 28 b are increased, joining strength (fixing strength)between the surrounding wall member 26 and the board 21 can beincreased. However, if the width Wb of the second portion 28 b and thethickness Tb of the second portion 28 b are excessively increased, adistance to a circuit component or the like provided outside thesurrounding wall member 26 becomes excessively long, and there is a fearthat the luminaire 1 can not be miniaturized. Thus, the width Wb of thesecond portion 28 b and the thickness Tb of the second portion 28 b arepreferably made as small as possible according to the required joiningstrength (fixing strength).

The second portion 28 b includes a surface 28 b 1 (corresponding to anexample of the first surface) inclined in a direction in which as a partthereof approaches the board 21 side, the part goes away from the outerwall 26 b of the surrounding wall member 26.

The surface 28 b 1 can be made a curved surface or can be made a flatsurface. Besides, when the surface 28 b 1 is made the curved surface,the surface can be made a concave curved surface as shown in FIG. 3 orcan be made a convex curved surface.

Incidentally, as described later, when the joining part 28 is formed byhardening a resin, the surface 28 b 1 can be made the concave curvedsurface.

The third portion 28 c is provided inside an inner wall 26 c of thesurrounding wall member 26, and covers at least a part of the inner wall26 c of the surrounding wall member 26.

A thickness Tc of the third portion 28 c is larger than the thickness Taof the first portion 28 a.

The thickness Tc of the third portion 28 c can be made smaller than thethickness Tb of the second portion 28 b.

Incidentally, the thickness Tc of the third portion 28 c is a size fromthe surface of the board 21 to the highest position attached to theinner wall 26 c of the surrounding wall member 26.

The third portion 28 c includes a surface 28 c 1 (corresponding to anexample of the second surface) inclined in a direction in which as apart thereof approaches the board 21 side, the part goes away from theinner wall 26 c of the surrounding wall member 26.

The surface 28 c 1 can be made a curved surface or can be made a flatsurface. Besides, when the surface 28 c 1 is made the curved surface,the surface can be made a concave curved surface as shown in FIG. 3 orcan be made a convex curved surface.

Incidentally, as described later, when the joining part 28 is formed byhardening a resin, the surface 28 c 1 can be made the concave curvedsurface.

The joining part 28 (the first portion 28 a, the second portion 28 b andthe third portion 28 c) is made of a mixture of resin, such as siliconeresin or epoxy resin, and particles of titanium oxide or the like).

The reflectivity of the joining part 28 to the light emitted from thelight-emitting element 22 is higher than that of the board 21 or thewiring pattern 24.

When the joining part 28 is formed by using the material as statedabove, since the reflectivity to the light emitted from thelight-emitting element 22 can be made higher than the board 21 or thewiring pattern 24, the light extraction efficiency can be improved.

Incidentally, no limitation is made to the particles of titanium oxide,and particles made of a material having a high reflectivity to the lightemitted from the light-emitting element 22 has only to be mixed.

The joining part 28 can be formed by, for example, a followingprocedure.

First, a resin, such as silicone resin or epoxy resin, particles oftitanium oxide or the like, a solvent and the like are mixed to form anadhesive having fluidity.

Next, the adhesive is applied to a specified position on the board 21 byusing a dispenser or the like.

Subsequently, the surrounding wall member 26 is pressed to the appliedadhesive, and the adhesive is made to flow out to the outside and theinside of the surrounding wall member 26.

At this time, the adhesive creeps up the outer wall 26 b of thesurrounding wall member 26 and the inner wall 26 c of the surroundingwall member 26, and the surface 28 b 1 and the surface 28 c 1 areformed.

Thereafter, the adhesive is hardened by evaporating the solvent and thelike, and the joining part 28 is formed. The board 21 and thesurrounding wall member 26 are joined through the joining part 28.

Incidentally, the adhesive can be made a mixture of an adhesivecontaining a resin, such as silicone resin or epoxy resin, and particlesof titanium oxide or the like.

Next, the third portion 28 c will be further described.

FIG. 4 and FIG. 5 are schematic sectional views for exemplifying a formof the third portion 28 c.

Incidentally, FIG. 4 and FIG. 5 are schematic enlarged views of a part Bin FIG. 3.

As shown in FIG. 4 and FIG. 5, the inner wall 26 c of the surroundingwall member 26 is almost parallel to a light emitting direction (frontdirection of the luminaire 1).

Thus, the light emitted from the light-emitting element 22 and incidenton the inner wall 26 c of the surrounding wall member 26 becomes hard tobe emitted to the front side of the luminaire 1, and there is a fearthat the light extraction efficiency can not be improved.

As shown in FIG. 4 and FIG. 5, if the inner wall 26 c of the surroundingwall member 26 is covered with the third portion 28 c, light reflectedby the inner wall 26 c of the surrounding wall member 26 can bedecreased. Besides, as described before, the surrounding wall member 26is formed of the material having the high reflectivity to the lightemitted from the light-emitting element 22. As a result, the lightextraction efficiency can be increased.

In recent years, there is a tendency that a thickness Td of thelight-emitting element 22 becomes small (thickness of the light-emittingelement 22 becomes thin).

Besides, when consideration is given to that the surrounding wall member26 is formed using a forming die or the like, a height H of the innerwall 26 c is required to have a certain degree of length.

Thus, as shown in FIG. 5, the upper surface of the light-emittingelement 22 as the light-emitting surface is lower than the upper endposition of the inner wall 26 c.

As a result, there is a tendency that the light emitted from thelight-emitting element 22 becomes easily incident on the inner wall 26 cof the surrounding wall member 26.

In this embodiment, since the third portion 28 c covers the inner wall26 c of the surrounding wall member 26, even if the thickness Td of thelight-emitting element 22 becomes small, the light extraction efficiencycan be improved.

Besides, in general, the reflectivity of the surface of the board 21 islow for the light emitted from the light-emitting element 22. Thus, ifthe width Wc of the third portion 28 c is increased, the lightextraction efficiency can be improved.

Incidentally, the width Wc of the third portion 28 c is a size from theinner wall 26 c of the surrounding wall member 26 to the farthestposition from the inner wall 26 c attached to the surface of the board21.

According to the knowledge obtained by the inventor, when a distancebetween the inner wall 26 c of the surrounding wall member 26 and an endface of the light-emitting element 22 is L, if Wc≧L/2 is established,the light extraction efficiency can be improved.

Incidentally, the surface of the board 21 exposed at the inside of thesurrounding wall member 26 may be covered with the third portion 28 c.

According to the embodiment exemplified above, the luminaire can berealized in which the airtightness between the surrounding wall memberand the board, the resistance to external stress and heat shock, and thelight extraction efficiency can be improved.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions. Moreover, above-mentioned embodiments can becombined mutually and can be carried out.

What is claimed is:
 1. A luminaire comprising: a board provided in amain body part; a light-emitting element provided on a surface of theboard; a surrounding wall member provided to surround the light-emittingelement: and a joining part including a first portion which is providedbetween the board and the surrounding wall member and a second portionwhich is provided outside the surrounding wall member and covers atleast a part of an outer wall of the surrounding wall member.
 2. Theluminaire according to claim 1, wherein the joining part furtherincludes a third portion which is provided inside the surrounding wallmember and covers at least a part of an inner wall of the surroundingwall member.
 3. The luminaire according to claim 1, wherein areflectivity of the joining part to light emitted from thelight-emitting element is higher than that of one of the board and awiring pattern.
 4. The luminaire according to claim 2, wherein afollowing expression is satisfied:Wc≧L/2 where a width of the third portion is Wc, and a distance betweenthe inner wall of the surrounding wall member and an end face of thelight-emitting element is L.
 5. The luminaire according to claim 1,wherein the light-emitting element is electrically connected to a wiringpattern provided on the surface of the board, and the luminaire furthercomprises: a power-supply terminal electrically connected to the wiringpattern; and a socket fitted to the power-supply terminal.
 6. Theluminaire according to claim 1, wherein the first portion is membranous.7. The luminaire according to claim 1, wherein a thickness of the secondportion is larger than a thickness of the first portion.
 8. Theluminaire according to claim 1, wherein the second portion includes afirst surface inclined in a direction in which as a part thereofapproaches the board side, the part goes away from an outer wall of thesurrounding wall member.
 9. The luminaire according to claim 8, whereinthe first surface is one of a concave curved surface, a convex curvedsurface and a flat surface.
 10. The luminaire according to claim 2,wherein a thickness of the third portion is larger than a thickness ofthe first portion.
 11. The luminaire according to claim 2, wherein athickness of the third portion is smaller than a thickness of the secondportion.
 12. The luminaire according to claim 2, wherein the thirdportion includes a second surface inclined in a direction in which as apart thereof approaches the board side, the part goes away from theinner wall of the surrounding wall member.
 13. The luminaire accordingto claim 12, wherein the second surface is one of a concave curvedsurface, a convex curved surface and a flat surface.
 14. The luminaireaccording to claim 2, wherein the third portion covers a surface of theboard exposed at the inside of the surrounding wall member.
 15. Theluminaire according to claim 1, wherein the joining part includes aresin and a particle made of a material having a high reflectivity tolight emitted from the light-emitting element.
 16. The luminaireaccording to claim 15, wherein the resin is one of silicone resin andepoxy resin, and the material having the high reflectivity to the lightemitted from the light-emitting element is titanium oxide.
 17. Theluminaire according to claim 2, wherein the inner wall of thesurrounding wall member is parallel to a front direction of theluminaire.
 18. The luminaire according to claim 1, wherein thesurrounding wall member is annular-shaped.
 19. The luminaire accordingto claim 1, further comprising a sealing part provided at a center partof the surrounding wall member.
 20. The luminaire according to claim 19,wherein the sealing part includes a translucent material and a phosphor.